Field
The present disclosure generally relates to an apparatus and method for preparing and analyzing gaseous samples.
Description of the Related Art
In oil and gas extraction, drilling a wellbore generally includes circulating a mud or mud-like substance around the drill bit during drilling operations. This mud or mud-like substance is generally referred to as “drilling mud” and has a variety of potential formulations. Drilling mud serves a number of functions in drilling operations, such as, for example, temperature control of the drill bit, removal of drill cuttings, and counterbalancing formation pressures via hydrostatic pressure.
During drilling operations, it is a common practice to analyze the drilling mud that is returned to the surface after being in proximity to the drill bit. This analysis provides a means for gathering information about the formation through which the wellbore is being drilled. Specifically, oil and gas explorers are often interested in analysis of gases evolved or extracted from the drilling mud. Gas obtained from drilling mud is commonly referred to as “mudgas,” and analysis of such gas may be referred to as “mudgas analysis.” Mudgas analysis can be used, for example, to detect the presence of hydrocarbons in the wellbore.
When mudgas analysis is performed on samples corresponding to various wellbore depths, mudgas compositions may help to indicate “pay zones” (hydrocarbon-rich zones) within the formation or otherwise to characterize the formation. A mudgas analysis of particular interest in oil and gas exploration is the isotopic analysis of hydrocarbons present in mud samples. For example, the 13C/12C ratio of methane in the mudgas may indicate whether the hydrocarbons present in the sample originate from biogenic or thermogenic processes, which in turn may indicate whether liquid petroleum is present in the formation. Additionally, biogenic hydrocarbons are more likely to be spurious indications of recoverable hydrocarbon deposits.
Current methods of mudgas analysis typically require expensive, delicate, and large equipment that is unsuitable or incompatible with drill site operations, thus, generally, mudgas analysis is conducted in laboratories located away from the drill site. Offsite mudgas analysis can result in significant delays between the sampling time and return of results. Delays hinder the usefulness of mudgas analysis in drilling operations, as such an apparatus and a method allowing reliable analytical results on variable feedstocks, such as mudgas, to be quickly obtained is required.